Control: Two experiments will be carried out to evaluate the effectiveness of anthelmintic therapy (albendazole) of male and female breeding Beagle dogs in controlling F. hirthi infection among their progeny. One, a parallel controlled experiment involving the progeny of 21 treated and 21 untreated F. hirthi infected breeding females, should be completed within a few months. The second, tandem controlled experiment, involving medication of some 2400 breeding animals at two establishments will extend beyond the period covered by this grant. Bionomics: The migration and development of F. hirthi larvae will be characterized as completely as possible within the limits of time and resources. We will try to perfect our in vitro culture technique and make it quantitative so that it may be used to assay the effects of physical and chemical influences on viability and development potential of first stage larvae.